Regulatory & Policy

BridgeBio files NDA for BBP-418 in limb-girdle muscular dystrophy type 2I/R9

Edited by Robert McTiernan··4 min read

BridgeBio Pharma submitted a New Drug Application to the US FDA on 30 March 2026 for oral BBP-418, seeking approval for the treatment of individuals living with limb-girdle muscular dystrophy type 2I/R9 (LGMD2I/R9). The filing, the first NDA submission for BBP-418, is supported by interim data from the Phase III FORTIFY trial and, if approved, would represent the first authorised therapy for any form of limb-girdle muscular dystrophy — a group of rare inherited neuromuscular diseases for which no disease-modifying treatment currently exists.

The NDA filing seeks approval for an oral formulation of BBP-418 in adults with LGMD2I/R9, a monogenic autosomal recessive disease caused by partial loss-of-function mutations in the fukutin-related protein (FKRP) gene. FKRP mutations impair glycosylation of alpha-dystroglycan, a protein that stabilises muscle cell membranes, leading to progressive skeletal, pulmonary, and cardiac muscle deterioration. The company said it anticipates a US launch in late 2026 or early 2027, based on ongoing discussions with the agency. BBP-418 holds Orphan Drug, Fast Track, and Rare Pediatric Disease Designations from the US FDA, as well as Orphan Drug Designation from the European Medicines Agency. The company stated its hope that the NDA may be eligible for Priority Review given the Fast Track designation and the absence of approved therapies in this indication. BridgeBio also said it is engaging European regulators to identify an expedited path to approval on that continent.

The NDA submission is anchored by interim data from FORTIFY, the Phase III clinical trial of BBP-418 in LGMD2I/R9. The company said the trial met all pre-specified primary and secondary endpoints at its 12-month interim analysis, with statistically significant improvements in ambulation and pulmonary function. According to data presented at the 2026 MDA Clinical and Scientific Conference, participants receiving BBP-418 completed the 100-metre timed test approximately 31 seconds faster than those on placebo at 12 months, with separation from placebo observed as early as three months. On the 10-metre walk test, the BBP-418 group showed a mean change from baseline of +0.13 m/s compared with −0.10 m/s in the placebo group. Reductions in serum creatine kinase — a biomarker of muscle damage — were also reported, with 59.6% of participants treated for 12 months achieving levels within twice the upper limit of normal and 38.3% achieving normalisation.

On safety, no treatment-related serious adverse events or deaths were recorded. Diarrhea was the most frequently reported adverse event in the BBP-418 group but was characterized as Grade 1–2 only.

BBP-418's differentiated approach to LGMD

LGMD2I/R9 is a disease that varies by genotype. Individuals with the homozygous L276I mutation typically develop symptoms in late childhood, with approximately 25% losing independent ambulation, 10% requiring assisted ventilation, and 30% developing cardiomyopathy in adulthood. Those with other FKRP genotypes face an earlier and more severe course, with rapid loss of mobility by age 20, cardiac involvement in around 60% of cases, and near-universal pulmonary decline by age 30. Cardiomyopathy progresses at an estimated annual rate of 0.4% loss of left ventricular ejection fraction. Current management is limited to physical therapy, respiratory support, cardiac monitoring, and symptomatic care — none of which address the underlying glycosylation defect.

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BBP-418 acts through substrate supplementation: the compound provides excess ribitol, a precursor to ribitol-5-phosphate, which saturates the residual enzymatic activity of mutant FKRP and thereby restores alpha-dystroglycan glycosylation. This mechanism is distinct from the gene therapy approaches being pursued for other LGMD subtypes. Sarepta Therapeutics, for instance, is in the latter stages of development with SRP-9003, an adeno-associated virus gene therapy targeting LGMD2E/R4, a subtype caused by mutations in the beta-sarcoglycan gene. The broader LGMD landscape encompasses more than 30 genetically defined subtypes, and the field has seen growing interest in both small-molecule and gene therapy approaches, though no product has yet reached approval for any of them.

The oral route of administration for BBP-418 is a practical consideration in a patient population that frequently experiences progressive loss of mobility. Gene therapies under development for various LGMD subtypes typically require intravenous infusion and carry distinct manufacturing, immunogenicity, and re-dosing constraints. BridgeBio said it intends to initiate clinical studies of BBP-418 in LGMD2I/R9 for individuals under 12 years of age, as well as in LGMD2M and LGMD2U — subtypes also linked to FKRP pathway dysfunction — in the near future. The company also noted that, consistent with its Rare Pediatric Disease Designation, it may qualify for a Priority Review Voucher upon approval.

The BridgeBio NDA submission adds to a small but expanding set of regulatory filings in the broader neuromuscular disease space, where the intersection of genetic specificity and functional endpoint measurement continues to shape trial design and regulatory strategy. The US FDA has not yet confirmed acceptance of the filing for review, and no PDUFA date has been publicly disclosed. The application remains under initial agency assessment.

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